Maintaining time alignment with multiple uplink carriers

ABSTRACT

Maintaining time alignment with multiple carriers is contemplated. A group of uplink carriers (UL CC sets) that operate with a single Timing Advance (TA) may be determined, and a TA value may be applied to a specific UL CC set. A wireless transmit/receive unit&#39;s (WTRU) capability of using multiple TAs may define a group index of a few bits for each UL CC set. A TA Command received in a Random Access Response message may be used to apply the TA value to each UL carrier of the UL CC set. The WTRU may determine which UL CC set the TA value applies to based on which DL carrier the command was transmitted from. The WTRU may determine which UL CC set the TA value applies to based on the Group Index being explicitly provided in the command. The WTRU may release multi-CC configurations upon Time Alignment Timer (TAT) expiry.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.12/986,549, titled “MAINTAINING TIME ALIGNMENT WITH MULTIPLE UPLINKCARRIERS”, filed Jan. 7, 2011, which claims the benefit of U.S.Provisional Application No. 61/293,271, filed Jan. 8, 2010, titled“METHOD OF MAINTAINING TIME ALIGNMENT WITH MULTIPLE UPLINK CARRIERS”,U.S. Provisional Application No. 61/320,449, filed Apr. 2, 2010, titled“METHOD AND APPARATUS FOR MAINTAINING TIME ALIGNMENT WITH MULTIPLEUPLINK CARRIERS”, and U.S. Provisional Application No. 61/323,680, filedApr. 13, 2010, titled “METHOD AND APPARATUS FOR MAINTAINING TIMEALIGNMENT WITH MULTIPLE UPLINK CARRIERS”, the contents of all theaforementioned applications are hereby incorporated by reference as ifset forth herein in their respective entirety, for all purposes.

BACKGROUND

In wireless communication systems, such as in an Long Term Evolution(LTE) wireless system, the network may configure the wirelesstransmit/receive unit (WTRU) with uplink (UL) and downlink (DL)resources on a single uplink (UL) and single downlink (DL) carrierrespectively. In order to utilize these resources, the WTRU may beexpected to be in sync with the network on these carriers.

Resources may need to be consumed to determine the synchronization andalignment status between the WTRU and the network via the single UL/DL,carrier. More resources may be necessary to determine synchronizationand alignment between the WTRU and the network where multiple uplinkcarriers may be available to the WTRU.

SUMMARY

This Summary is provided to introduce a selection of concepts in asimplified form that are further described below in the DetailedDescription. This Summary is not intended to identify key features oressential features of the claimed subject matter, nor is it intended tobe used to limit the scope of the claimed subject matter. Furthermore,the claimed subject matter is not limited to limitations that solve anyor all disadvantages noted in any part of this disclosure.

Disclosed herein are ways for maintaining time alignment with multiplecarriers. A group of uplink carriers (UL CC sets) that operate with asingle Timing Advance (TA) are determined, and a TA value may be appliedto a specific UL CC set. A wireless transmit/receive unit's (WTRU's)capability of using multiple TAs may define a group index of a few bitsfor each UL CC set. A TA Command received in a Random Access Responsemessage may be used to apply the TA value to each UL carrier of the ULCC set. The WTRU may determine which UL CC set the TA value applies tobased on which DL carrier the command was received onto. The WTRU maydetermine which UL CC set the TA value applies to based on the GroupIndex being explicitly provided in the command. The WTRU may releasemulti-CC configurations upon a timeAlignmentTimer (TAT) expiry.

Embodiments contemplate a wireless transmit/receive unit (WTRU) that maybe configured, at least in part, to identify one or more uplink carrierswith which the WTRU may be capable of operating, or one or more uplinkcarriers that are operating on a wireless network. The WTRU may also beconfigured to determine one or more uplink component carrier sets (UL CCsets). Each of the UL CC sets may comprise one or more of the uplinkcarriers and each of the one or more uplink carriers that may comprise arespective UL CC set may be capable of operating with the same TimingAdvance (TA). The WTRU may be configured to determine the one or moregroups of UL CC sets based on a predetermined identification of which ofthe one or more uplink carriers may correspond to the one or more UL CCsets. For example, the predetermined identification may be receivedusing dedicated signaling or may be inferred based on one or moreproperties of the respective UL CC sets. The WTRU may also be configuredto select at least one UL CC set and identify at least one of the one ormore uplink, carriers that may be capable of random access channel(RACH) communication for the selected at least one UL CC set. The WTRUmay be configured to initiate a RACH communication on at least one ofthe identified one or more uplink carriers for the selected at least oneUL CC set and to receive a TA value in response to the RACHcommunication. The WTRU′ may be further configured to apply the TA valueto each of the one or more uplink carriers that comprise the selected atleast one UL CC set.

Embodiments contemplate that the selected at least one UL CC set mayhave an associated Time Alignment Timer (TAT) and the WTRU may befurther configured to either start the TAT or restart the TAT. The WTRUmay also be configured to receive a signal via a downlink carrier wherethe signal may include a TA value. The WTRU may identify at least one ofthe one or more uplink carriers that may be paired with the downlinkcarrier and identify at least one of the one or more UL CC sets that maycorrespond to the at least one of the one or more uplink carriers thatmay be paired with the downlink carrier. The WTRU may apply the TA valueto each of the one or more uplink carriers that comprise the identifiedat least one of the one or more UL CC sets.

Embodiments contemplate that one or more UL CC sets may correspond afrequency band of their respective serving cell and the WTRU may beconfigured to receive a signal via a downlink carrier, where the signalmay include a TA value. The WTRU may be configured to identify afrequency band corresponding to the downlink carrier and identify atleast one of the one or more UL CC sets whose respective frequency bandmay correspond to the frequency band of the downlink carrier. The WTRUmay apply the TA value to each of the one or more uplink carriers thatmay comprise the identified at least one of the one or more UL CC sets.

Embodiments contemplate that the a selected at least one UL CC set mayincludes at least one uplink carrier with a dedicated physical uplinkcontrol channel (PUCCH) configuration. A WTRU may be configured to ceasetransmitting on a resource corresponding to the PUCCH upon an expirationof the TAT. Alternatively or additionally, the WTRU may be configured toremove at least a part of the PUCCH configuration upon an expiration ofthe TAT. Also alternatively or additionally, the WTRU may be configuredto remove one or more RACH resources from the configuration of theselected at least one UL CC set upon an expiration of the TAT.

Embodiments contemplate that a wireless network resource, such as anevolved Node B (eNodeB), may be configured, at least in part, toidentify one or more uplink carriers with which the eNodeB may becapable of operating. The eNodeB may determine one or more indices. Eachof the one or more indices may correspond respectively to one or moreuplink component carrier sets (UL CC sets). Also, each of the UL CC setsmay comprise one or more of the uplink carriers, and each of the one ormore uplink carriers that comprise a respective UL CC set may be capableof operating with the same Timing Advance (TA). The eNodeB may beconfigured to transmit the one or more indices.

Embodiments contemplate that the eNodeB may be configured to receive aRACH communication on at least one of the one or more uplink carriersthat comprise at least one of the one or more UL CC sets. The eNodeB maytransmit a TA value in response to the RACH communication. The TA valuemay be applicable to each of the one or more uplink carriers thatcomprise the at least one of the one or more UL CC sets. The eNode B maybe configured to transmit a signal, where the signal may include a TAvalue and an indicator. The indicator may indicate at least one of theone or more UL CC sets to which the TA value may be applicable. TheeNodeB may be configured to receive a RACH communication on at least oneof the one or more uplink carriers of the UL CC set and may transmit aTA value in response to the RACH communication. The TA value may beapplicable to each of the one or more uplink carriers that comprise theUL CC set. Alternatively or additionally, the epode B may be configuredto transmit a signal, where the signal may include a TA value and anindicator. The indicator may indicate the UL CC set to which the TAvalue may be applicable.

Embodiments contemplate that a wireless transmit/receive unit (WTRU),may comprise a processor that may be configured to determine one or moresets of serving cells. Each of the one or more sets of serving cells mayinclude at least one serving cell with a configured uplink componentcarrier (UL CC sets). Each of the UL CC sets may be respectivelyassociated with a group index of one or more group indices. Each UL CCset of the one or more UL CC sets may respectively include one or moreuplink carriers that may be associated with the same group index withwhich the UL CC set is associated. Each of the one or more uplinkcarriers that may be included in a respective UL CC set may beconfigured to operate with the same Timing Advance (TA) of one or moreTiming Advances (TAs). Each of the UL CC sets may have a respectivelyassociated reference carrier providing a TA of the one or more TAs. Theprocessor may be configured to receive a first TA value via a firstreference carrier. The first reference carrier may be associated with afirst UL CC set. The processor may be configured to apply the first TAvalue to the one or more uplink carriers that may be included in thefirst UL CC set.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed, understanding may be had from the followingdescription, given by way of example in conjunction with theaccompanying drawings wherein:

FIG. 1A is a system diagram of an example communications system in whichone or more disclosed embodiments may be implemented;

FIG. 1B is a system diagram of an example wireless transmit/receive unit(WTRU) that may be used within the communications system illustrated inFIG. 1A;

FIG. 1C is a system diagram of an example radio access network and anexample core network that may be used within the communications systemillustrated in FIG. 1A;

FIG. 2 illustrates a flow chart of an exemplary method consistent withembodiments;

FIG. 3 illustrates a flow chart of an exemplary method consistent withembodiments;

FIG. 4 illustrates a flow chart of an exemplary method consistent withembodiments;

FIG. 5 illustrates a flow chart of an exemplary method consistent withembodiments; and

FIG. 6 illustrates a flow chart of an exemplary method consistent withembodiments.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

FIG. 1A is a diagram of an example communications system 100 in whichone or more disclosed embodiments may be implemented. The communicationssystem 100 may be a multiple access system that provides content, suchas voice, data, video, messaging, broadcast, etc., to multiple wirelessusers. The communications system 100 may enable multiple wireless usersto access such content through the sharing of system resources,including wireless bandwidth. For example, the communications systems100 may employ one or more channel access methods, such as code divisionmultiple access (CDMA), time division multiple access (TDMA), frequencydivision multiple access (FDMA), orthogonal FDMA (OFDMA), single-carrierFDMA (SC-FDMA), and the like.

As shown in FIG. 1A, the communications system 100 may include wirelesstransmit/receive units (WTRUs) 102 a, 102 b, 102 c, 102 d, a radioaccess network (RAN) 104, a core network 106, a public switchedtelephone network (PSTN) 108, the Internet 110, and other networks 112,though it will be appreciated that the disclosed embodiments contemplateany number of WTRUs, base stations, networks, and/or network elements.Each of the WTRUs 102 a, 102 b, 102 c, 102 d may be any type of deviceconfigured to operate and/or communicate in a wireless environment. Byway of example, the WTRUs 102 a, 102 b, 102 c, 102 d may be configuredto transmit and/or receive wireless signals and may include userequipment (UE), a mobile station, a fixed or mobile subscriber unit, apager, a cellular telephone, a personal digital assistant (PDA), asmartphone, a laptop, a netbook, a personal computer, a wireless sensor,consumer electronics, and the like.

The communications systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a, 114 b may be anytype of device configured to wirelessly interface with at least one ofthe WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one or morecommunication networks, such as the core network 106, the Internet 110,and/or the networks 112. By way of example, the base stations 114 a, 114b may be a base transceiver station (BTS), a Node-B, an eNode B, a HomeNode B, a Home eNode B, a site controller, an access point (AP), awireless router, and the like. While the base stations 114 a, 114 b areeach depicted as a single element, it will be appreciated that the basestations 114 a, 114 b may include any number of interconnected basestations and/or network elements.

The base station 114 a may be part of the RAN 104, which may alsoinclude other base stations and/or network elements (not shown), such asa base station controller (BSC), a radio network controller (RNC), relaynodes, etc. The base station 114 a and/or the base station 114 b may beconfigured to transmit and/or receive wireless signals within aparticular geographic region, which may be referred to as a cell (notshown). The cell may further be divided into cell sectors. For example,the cell associated with the base station 114 a may be divided intothree sectors. Thus, in one embodiment, the base station 114 a mayinclude three transceivers, e.g., one for each sector of the cell. Inanother embodiment, the base station 114 a may employ multiple-inputmultiple output (MIMO) technology and, therefore, may utilize multipletransceivers for each sector of the cell.

The base stations 114 a, 114 b may communicate with one or more of theWTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, which may beany suitable wireless communication link (e.g., radio frequency (RF),microwave, infrared (IR), ultraviolet (UV), visible light, etc.). Theair interface 116 may be established using any suitable radio accesstechnology (RAT).

More specifically, as noted above, the communications system 100 may bea multiple access system and may employ one or more channel accessschemes, such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA, and the like. Forexample, the base station 114 a in the RAN 104 and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Universal MobileTelecommunications System (UMTS) Terrestrial Radio Access (UTRM, whichmay establish the air interface 116 using wideband CDMA (WCDMA). WCDMAmay include communication protocols such as High-Speed Packet Access(HSPA) and/or Evolved HSPA (HSPA+). HSPA may include High-Speed DownlinkPacket Access (HSDPA) and/or High-Speed Uplink Packet Access (HSUPA).

In another embodiment, the base station 114 a and the WTRUs 102 a, 102b, 102 c may implement a radio technology such as Evolved UMTSTerrestrial Radio Access (E-UTRA), which may establish the air interface116 using Long Term Evolution (LTE) and/or LTE-Advanced (LTE-A).

In other embodiments, the base station 114 a and the WTRUs 102 a, 102 b,102 c may implement radio technologies such as IEEE 802.16 (e.g.,Worldwide Interoperability for Microwave Access (WiMAX)), CDMA2000,CDMA2000 1×, CDMA2000 EV-DO, Interim Standard 2000 (IS-2000), InterimStandard 95 (IS-95), Interim Standard 856 (IS-856), Global System forMobile communications (GSM), Enhanced Data rates for GSM Evolution(EDGE), GSM EDGE (GERAN), and the like.

The base station 114 b in FIG. 1A may be a wireless router, Home Node B,Home eNode B, or access point, for example, and may utilize any suitableRAT for facilitating wireless connectivity in a localized area, such asa place of business, a home, a vehicle, a campus, and the like. In oneembodiment, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In another embodiment, the base station 114 band the WTRUs 102 c, 102 d may implement a radio technology such as IEEE802.15 to establish a wireless personal area network (WPAN). In yetanother embodiment, the base station 114 b and the WTRUs 102 c, 102 dmay utilize a cellular-based RAT (e.g., WCDMA, CDMA2000, GSM, LTE,LTE-A, etc.) to establish a picocell or femtocell. As shown in FIG. 1A,the base station 114 b may have a direct connection to the Internet 110.Thus, the base station 114 b may not be required to access the Internet110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice over internee protocol (VoIP) services to one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d. For example, the core network 106may provide call control, billing services, mobile location-basedservices, pre-paid calling, Internet connectivity, video distribution,etc., and/or perform high-level security functions, such as userauthentication. Although not shown in FIG. 1A, it will be appreciatedthat the RAN 104 and/or the core network 106 may be in direct orindirect communication with other RANs that employ the same RAT as theRAN 104 or a different RAT. For example, in addition to being connectedto the RAN 104, which may be utilizing an E-UTRA radio technology, thecore network 106 may also be in communication with another RAN (notshown) employing a GSM radio technology.

The core network 106 may also serve as a gateway for the WTRUs 102 a,102 b, 102 c, 102 d to access the PSTN 108, the Internet 110, and/orother networks 112. The PSTN 108 may include circuit-switched telephonenetworks that provide plain old telephone service (POTS). The Internet110 may include a global system of interconnected computer networks anddevices that use common communication, protocols, such as thetransmission control protocol (TCP), user datagram protocol (UDP) andthe internet protocol (IP) in the TCP/IP internet protocol suite. Thenetworks 112 may include wired or wireless communications networks ownedand/or operated by other service providers. For example, the networks112 may include another core network connected to one or more RANs,which may employ the same RAT as the RAN 104 or a different RAT.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in thecommunications system 100 may include multi-mode capabilities, e.g., theWTRUs 102 a, 102 b, 102 c, 102 d may include multiple transceivers forcommunicating with different wireless networks over different wirelesslinks. For example, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology.

FIG. 1B is a system diagram of an example WTRU 102. As shown in FIG. 1B,the WTRU 102 may include a processor 118, a transceiver 120, atransmit/receive element 122, a speaker/microphone 124, a keypad 126, adisplay/touchpad 128, non-removable memory 130, removable memory 132, apower source 134, a global positioning system (GPS) chipset 136, andother peripherals 138. It will be appreciated that the WTRU 102 mayinclude any sub-combination of the foregoing elements while remainingconsistent, with an embodiment.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), aplurality of microprocessors, one or more microprocessors in associationwith a DSP core, a controller, a microcontroller, Application SpecificIntegrated Circuits (ASICs), Field Programmable Gate Array (FPGAs)circuits, any other type of integrated circuit (IC), a state machine,and the like. The processor 118 may perform signal coding, dataprocessing, power control, input/output processing, and/or any otherfunctionality that enables the WTRU 102 to operate in a wirelessenvironment. The processor 118 may be coupled to the transceiver 120,which may be coupled to the transmit/receive element 122. While FIG. 1Bdepicts the processor 118 and the transceiver 120 as separatecomponents, it will be appreciated that the processor 118 and thetransceiver 120 may be integrated together in an electronic package orchip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over the air interface 116. For example, in one embodiment, thetransmit/receive element 122 may be an antenna configured to transmitand/or receive RF signals. In another embodiment, the transmit/receiveelement 122 may be an emitter/detector configured to transmit and/orreceive IR, UV, or visible light signals, for example. In yet anotherembodiment, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. It will be appreciatedthat the transmit/receive element 122 may be configured to transmitand/or receive any combination of wireless signals.

In addition, although the transmit/receive element 122 is depicted inFIG. 1B as a single element, the WTRU 102 may include any number oftransmit/receive elements 122. More specifically, the WTRU 102 mayemploy MIMO technology. Thus, in one embodiment, the WTRU 102 mayinclude two or more transmit/receive elements 122 (e.g., multipleantennas) for transmitting and receiving wireless signals over the airinterface 116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and to demodulatethe signals that are received by the transmit/receive element 122. Asnoted above, the WTRU 102 may have multi-mode capabilities. Thus, thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11, forexample.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit or organic light-emitting diode (OLED) display unit). The processor118 may also output user data to the speaker/microphone 124, the keypad126, and/or the display/touchpad 128. In addition, the processor 118 mayaccess information from, and store data in, any type of suitable memory,such as the non-removable memory 106 and/or the removable memory 132.The non-removable memory 106 may include random-access memory (RAM),read-only memory (ROM), a hard disk, or any other type of memory storagedevice. The removable memory 132 may include a subscriber identitymodule (SIM) card, a memory stick, a secure digital (SD) memory card,and the like. In other embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NIMH), lithium-ion (Li-ion),etc.), solar cells, fuel cells, and the like.

The processor 118 may also be coupled to the GPS chipset 136, which maybe configured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, 114 b) and/or determine itslocation based on the timing of the signals being received from two ormore nearby base stations. It will be appreciated that the WTRU 102 mayacquire location information by way of any suitablelocation-determination method while remaining consistent with anembodiment.

The processor 118 may further be coupled to other peripherals 138, whichmay include one or more software and/or hardware modules that provideadditional features, functionality and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, an Internetbrowser, and the like.

FIG. 1C is a system diagram of the RAN 104 and the core network 106according to an embodiment. As noted above, the RAN 104 may employ anE-UTRA radio technology to communicate with the WTRUs 102 a, 102 b,and/or 102 c over the air interface 116. The RAN 104 may also be incommunication with the core network 106.

The RAN 104 may include eNode-Bs 140 a, 140 b, 140 c, though it will beappreciated that the RAN 104 may include any number of eNode-Bs whileremaining consistent with an embodiment. The eNode-Bs 140 a, 140 b, 140c may each include one or more transceivers for communicating with theWTRUs 102 a, 102 b, 102 c over the air interface 116. In one embodiment,the eNode-Bs 140 a, 140 b, 140 c may implement MIMO technology. Thus,the eNode-B 140 a, for example, may use multiple antennas to transmitwireless signals to, and receive wireless signals from, the WTRU 102 a.

Each of the eNode-Bs 140 a, 140 b, 140 c may be associated with aparticular cell (not shown) and may be configured to handle radioresource management decisions, handover decisions, scheduling of usersin the uplink and/or downlink, and the like. As shown in FIG. 1C, theeNode-Bs 140 a, 140 b, 140 c may communicate with one another over an X2interface. The core network 106 shown in FIG. 1C may include a mobilitymanagement gateway (MME) 142, a serving gateway 144, and a packet datanetwork (PDN) gateway 146. While each of the foregoing elements aredepicted as part of the core network 106, it will be appreciated thatany one of these elements may be owned and/or operated by an entityother than the core network operator.

The MME 142 may be connected to each of the eNode-Bs 142 a, 142 b, 142 cin the RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, selecting aparticular serving gateway during an initial attach of the WTRUs 102 a,102 b, 102 c, and the like. The MME 142 may also provide a control planefunction for switching between the RAN 104 and other RANs (not shown)that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the eNode Bs 140 a,140 b, 140 c in the RAN 104 via the S1 interface. The serving gateway144 may generally route and forward user data packets to/from the WTRUs102 a, 102 b, 102 c. The serving gateway 144 may also perform otherfunctions, such as anchoring user planes during inter-eNode B handovers,triggering paging when downlink data is available for the WTRUs 102 a,102 b, 102 c, managing and storing contexts of the WTRUs 102 a, 102 b,102 c, and the like.

The serving gateway 144 may also be connected to the PDN gateway 146,which may provide the WTRUs 102 a, 102 b, 102 c with access topacket-switched networks, such as the Internet 110, to facilitatecommunications between the WTRUs 102 a, 102 b, 102 c and IP-enableddevices.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway (e.g.,an IP multimedia subsystem (IMS) server) that serves as an interfacebetween the core network 106 and the PSTN 108. In addition, the corenetwork 106 may provide the WTRUs 102 a, 102 b, 102 c with access to thenetworks 112, which may include other wired or wireless networks thatare owned and/or operated by other service providers.

When referred to hereafter, the term primary component carrier (PCC)includes, without loss of generality, a carrier of a WTRU configured tooperate with multiple component carriers for which some functionality,such as for example, derivation of security parameters and NASinformation, may be applicable only to that component carrier. The WTRUmay be configured with at least one PCC for the downlink (DL PCC) andone for the uplink (UL PCC). Consequently, a carrier which is not a PCCof the WTRU may hereafter be referred to as a Secondary Carrier (SCC).

The DL PCC may, for example, correspond to the CC used by the WTRU toderive initial security parameters when initially accessing the system.The UL PCC may, for example, correspond to the CC whose PUCCH resourcesare configured to carry all Hybrid Automatic Repeat Request (HARQ)Acknowledge/Negative Acknowledge (A/N) and Channel State Information(CSI) feedback for a given WTRU.

When referred to herein, the term “Component Carrier (CC)” includes,without loss of generality, a frequency on which the WTRU operates. Forexample, a WTRU may receive transmissions on a downlink CC (hereafter“DL CC”); a DL CC may comprise of a number of DL physical channelsincluding, but not limited to, the Physical Control Format IndicatorChannel (PCFICH), the Physical HARQ indicator Channel (PHICH), thePhysical Downlink Control Channel (PDCCH), the physical multicast datachannel (PMCH) and the Physical Downlink Shared Channel (PDSCH). On thePCFICH, the WTRU receives control data indicating the size of thecontrol region of the DL CC. On the PHICH, the WTRU receives controldata indicating HARQ ACK/NACK feedback for a previous uplinktransmission. On the PDCCH, the WTRU receives downlink controlinformation (DCIs) messages mainly used for the purpose of scheduling ofdownlink and uplink resources. On the PDSCH, the WTRU receives userand/or control data. For example, a WTRU may transmit on an uplink CC(hereafter “UL CC”); a UL CC may comprise of a number of UL physicalchannels including, but not limited to, the physical uplink controlchannel (PUCCH) and the physical uplink shared channel (PUSCH). On, thePUSCH, the WTRU transmits user and/or control data. On the PUCCH, and insome case on the PUSCH, the WTRU transmits uplink control information(such as CQI/PMI/RI or SR) and/or hybrid automatic repeat request (HARQ)acknowledgement/negative acknowledgement (ACK/NACK) feedback. On a ULCC, the WTRU may also be allocated dedicated resources for transmissionof Sounding and Reference Signals (SRS).

A cell typically minimally consists in a DL CC which is, in someembodiments, linked to a UL CC based on the system information (SI)received by the WTRU either broadcasted on the DL CC or possibly usingdedicated configuration signaling from the network. For example, whenbroadcasted on the DL CC, the WTRU receives the uplink frequency andbandwidth of the linked UL CC as part of the SystemInformationBlockType2(SIB2) information element.

When referred to herein, the term “Primary Cell (PCell)” includes,without loss of generality, the cell operating of the primary frequencyin which the WTRU either performs the initial connection establishmentprocedure or initiates the connection re-establishment procedure, or thecell indicated as the primary cell in the handover procedure. The WTRUuses the PCell to derive the parameters for the security functions andfor upper layer system information such as NAS mobility information.Other functions that may be supported only on the PCell DL includesystem information (SI) acquisition and change monitoring procedures onthe broadcast channel (BCCH), and paging. The UL CC of the PCell maycorrespond to the CC whose physical uplink control channel (PUCCH)resources are configured to carry all HARQ ACK/NACK feedback for a givenWTRU.

When referred to herein, the term “Secondary Cell (SCell)” includes,without loss of generality, the cell operating on a secondary frequencywhich may be configured once an RRC connection is established and whichmay be used to provide additional radio resources. System informationrelevant for operation in the concerned SCell is typically providedusing dedicated signaling when the SCell is added to the WTRU'sconfiguration. Although the parameters may have different values thanthose broadcasted on the downlink of the concerned SCell using thesystem information (SI) signaling, this information is herein referredto as SI of the concerned SCell independently of the method used by theWTRU to acquire this information.

When referred to herein, the terms “PCell DL” and “PCell UL” correspondsto, without loss of generality, the DL CC and the UL CC of the PCell,respectively. Similarly, the terms “SCell DL” and “SCell UL” correspondsto the DL CC and the UL CC (if configured) of a SCell, respectively. Forthe PCell, a CC may also be referred to as a PCC; for a SCell, a CC maybe referred to as a SCC.

When referred to herein, the term “serving cell” includes, without lossof generality, a primary cell (e.g, a PCell) or a secondary cell (e.g.,a SCell). More specifically, for a WTRU that is not configured with anySCell or that does not support operation on multiple component carriers(e.g., carrier aggregation), there is one serving cell comprising of thePCell, and in some embodiments perhaps there is only one serving cellcomprising of the PCell; for a WTRU that is configured with at least oneSCell, the term “serving cells” includes the set of one or more cellscomprising of the PCell and all configured SCell(s).

When a WTRU is configured with at, least one SCell, there is at leastone PCell DL (e.g. including one DL-SCH) and at least one PCell UL(e.g., including one UL-SCH) and, for each configured SCell, there is atleast one SCell DL and, in some embodiments, at least one SCell UL (ifconfigured). In some embodiments, there is always one PCell DL (e.g.including one DL-SCH) and one PCell UL (e.g., including one UL-SCH) and,for each configured SCell, there is one SCell DL and, in someembodiments, one SCell UL (if configured).

For R10 with Carrier Aggregation (CA), e.g., the WTRU has at least oneSCell DL in its configuration, the WTRU may also be configured with oneor more explicit resource allocations for A/N on PUCCH. In someembodiments, by way of example and not limitation, working assumptionsare made that include that PUCCH A/N resources may be explicitlyallocated for the UL PCC, for example using dedicated signaling; UL/DLPCC linking may be based on SI on DL PCC; SCell may be explicitly(de)activated; and a WTRU may perform RA in a SCC (e.g., RA-SR).

UL synchronization may be initially achieved using a random accesschannel (RACH) procedure, and the WTRU is considered to be UL TimeAligned with the network. The WTRU has a configurable timer, e.g.,timeAlignmentTimer (TAT) that may be used to maintain timing alignmentwith the network. A Release 8/Release 9 (R8/R9) WTRU releases aconfigured physical uplink control channel (PUCCH) resources for ChannelQuality Information/Precoding Matrix Indicator/Rank Indicator(CQI/PMI/RI), and also a sounding reference symbol (SRS) when the WTRUhas no valid Timing Advance, e.g., upon expiration of TA Timer. ForPUCCH resources for transmission of HARQ ACK/NACK (A/N), which aredynamically allocated, when TAT is not running the WTRU is not allowedto transmit A/N on PUCCH. For HARQ feedback on PUCCH, the resource onwhich to transmit on PUCCH is determined dynamically based on the firstControl Channel Element (CCE) of the DCI for the downlink (DL)assignment received on a physical downlink control channel (PDCCH).

A WTRU may be configured to operate with multiple carriers in theconnected mode. WTRU configuration may include more than one serving,cell with configured uplink resources, which corresponding uplinkcarriers may possibly be grouped based on similar timing alignmentrequirement in case the WTRU supports uplink carriers requiringdifferent Timing Advance. In such a scenario, the WTRU may need toestablish a valid Timing Alignment for each of these (groups of)carriers. One issue may be how the WTRU and the network agree on whichuplink carriers should share the same Timing Advance (TA). For purposeof example, and not limitation, the TA, may be the variable thatcontrols an adjustment of the time at which a WTRU may be allowed totransmit within allotted timeslots. Another issue may be how the networkcommunicates the TA values associated with these uplink carriers, orgroups thereof, to the WTRU. Yet another issue may be determining whatactions need to be taken by the WTRU when loss of synchronization occursdue to expiration of the timing advance timer for each uplink carrier,or a group thereof. Another issue may be how a WTRU, configured formulticarrier operation, handles: (1) PUCCH A/N resources when TAT isexpired for the UL CC on which the resources are configured, for examplethe PCell UL; and (2) SCell DLs when TAT is expired for the linked SCellUL.

Embodiments contemplate that a WTRU may transmit an A/N for the firstscheduled PDSCH transmission, e.g. a PDSCH assignment that is scheduledeither using PDCCH scrambled with C-RNTI, or otherwise on DL-SCHincluding the WTRU Contention Resolution Medium Access Control (MAC)control element (CE), after receiving a RAR message. A RAR message mayinclude a TA Command and may restart TAT during a RA procedure. If TATexpiry invalidates, for example, the R10 PUCCH AN resource, a rule maybe required for AN transmission for PDSCH received in a SCell DL, orelse a different mechanism may be needed to implicitly release the R10PUCCH AN resources such that the AN may be sent on the Physical UplinkControl Channel PUCCH dynamic resource according to R8 principles toensure compatibility.

Embodiments contemplate methods and techniques disclosed herein that mayfacilitate a WTRU to operate with multiple carriers in the connectedmode and may also maintain time alignment with multiple uplink carriers.

Embodiments contemplate that the Timing Advance (TA) value used by theWTRU for UL time alignment may be provided by the network in the RandomAccess Channel (RACH) response to the WTRU's RA CH request message, orby using a Timing Advance Command MAC Control Element. The WTRU may usethe TA value for UL time alignment. The WTRU may start/restart the TATassociated with the UL carrier because there may be one UL carrierassigned to the WTRU. In some instances, the WTRU may be constrained byits implementation to operate with a single TA for a group of ULcarriers that it may be operating with at a given time. This may be thecase if, for example, the UL carriers are within the same frequency bandand are transmitted using a common RF module. A group of carriersoperating with the same TA may be referred to herein as a “UL CC set”.

Embodiments contemplate that UL CC sets that may require minimumsignaling may include determining that or one or more UL carriers thatare a part of the same frequency band, are part of the same UL CC set.Those UL carriers that are not part of the same frequency band may notbe part of the same UL CC set. Also, embodiments contemplate that theWTRU and the network may know in advance which UL carriers belong to thesame UL CC set.

Embodiments contemplate that the definition of a UL CC set may depend onthe WTRU capability. The WTRU, therefore, may transmit information aspart of its E-UTRA capabilities to the network including which ULcarriers may be transmitted with different TAs. Since the possibility ofbeing able to operate with multiple TAs may be linked to the frequencybands the WTRU is supporting, defining the capability as a singleinformation element (“multipleTAsupport”) may be used to transfer thisinformation to the network. An example encoding may be:

Codepoint 0: WTRU is not capable of supporting multiple TAs;

Codepoint 1: WTRU is capable of operating with different TAs if ULcarriers are not in same band; and

Codepoint 2: WTRU is fully capable of operating with different TAs forany pair of UL carriers. Also by way of example, another contemplatedencoding may be:

Codepoint 0: WTRU is not capable of supporting multiple TAs (e.g. singleradio front end supporting a single frequency band);

Codepoint 1: WTRU is capable of operating with up to two different TAsif UL carriers are not in same band (e.g. dual radio front ends, eachsupporting a single frequency band); and

Codepoint 2: WTRU is fully capable of operating with different TAs forany number of UL carriers (e.g. full support for any combination offrequency band(s) according to the reported WTRU's capabilities andWTRU's class).

Using the encoded information, the network may define sets of ULcarriers that use the same timing advance (UL CC sets), and provide theinformation to the WTRU. The network may include UL carriers fromdifferent bands in the same UL CC set even if the WTRU is capable ofoperating with different TAs for UL carriers in different bands.

Some embodiments may identify UL carriers that use the same timingadvance by defining a group index of a few bits for each UL CC set(possibly a single bit if there is a maximum of 2 UL CC sets). The WTRUmay obtain the group index of the UL CC set to which an UL carrierbelongs when this UL carrier is being configured by the network (e.g.,in the RRC message). Alternatively, the group index may be broadcast inthe system information of a paired DL carrier. In another alternative, agroup index may be associated with a frequency band if the operationwith multiple timing advances within a band is not supported.

The WTRU may also obtain the DL carrier (or set of DL carriers) that maybe used as a reference for the timing advance for each UL carrier or ULCC set. The DL carrier, alternatively, that may be used as a referencefor the timing advance may be implicitly the DL carrier from which themessage including the timing advance value is transmitted.

Embodiments contemplate that a WTRU may apply different TA values fordifferent UL CC sets. Each UL CC set may operate with a separate TimeAlignment Timer (TAT). In accordance with this method, in oneembodiment, initial timing alignment may be achieved using a RandomAccess Channel (RACH) procedure wherein the TA value may be provided bythe network to the WTRU using the RACH response message. In case of anUL CC set where all the carriers (or a subset) of the set are configuredfor RACH, the WTRU may select one of the carriers that can be used forRACH and trigger the Random Access procedure. The Timing Advance Commandreceived in the Random Access Response message may then be used to applythe TA value to some or each UL carrier of the UL CC set, and the WTRUmay start/restart the TAT associated with the UL CC set.

In some embodiments only one carrier in the UL CC set may be configuredfor RACH. In such embodiments, the WTRU may trigger the Random Accessprocedure on this carrier, apply the TA value obtained in thecorresponding Random Access Response message to each UL carrier of theUL CC set, and start/restart the TAT associated with the UL CC set.

In other embodiments, the timing alignment may be maintained by theWTRU′ based on the TA value received from the network through either anexisting MAC CE or any other form of signaling. The WTRU may determinewhich UL CC set the TA value may apply to based on from which DL carrierthe command (for example, a Timing advance command MAC control element)was transmitted. For example, the UL CC set the TA value applies may bedetermined as the one to which the UL carrier paired to this DL carrierbelongs. In case a UL CC set corresponds to a frequency band, the TAvalue may apply to the UL CC set in the same band as the DL carrier fromwhich the command is transmitted. Alternatively, the correspondencebetween a DL carrier and an UL CC set may be explicitly signaled.

Embodiments contemplate that a frequency band may be defined for aserving cell, e.g., may be defined jointly for a DL carrier and, in someembodiments, a UL carrier forming the serving cell. Also the Timingadvance may be applied for some or all UL carriers of serving cells thatcorrespond to the same frequency band. Embodiments contemplate at leasttwo techniques to identify the applicable band for the time alignmentcommand (TAC). The applicable band may or may not be bound to thereception of the TAC in a specific downlink carrier which may itself bepart of the same frequency band. Embodiments contemplate that the TACmay be received and applied for some or all UL carriers of the frequencyband of the carrier on which it is received (e.g., implicitidentification of the applicable band). Alternatively or additionally,the TAC may be received anywhere and applied to all UL carriers of thefrequency band that may be indicated inside the TAC itself (e.g.,explicit identification of the applicable band).

Embodiments contemplate a MAC CE, that may include a TA, may be receivedon the DL of a serving cell. The WTRU may determine what UL CC set theserving cell's corresponding UL CC may belong to. The WTRU may apply thereceived TA to the UL CC of all of the serving cell (and/or to all ULCCs) that may belong to determined UL CC set. Embodiments contemplatethat the paring of an UL CC with a DL CC may be unique (e.g., 1 UL for 1DL). Embodiments also contemplate that, the pairs may be part of a set,where the criteria for being part of a set may be that all UL CCs of aset have the same TA requirement.

Alternatively, the WTRU may determine which UL CC set the TA valueapplies to based on the Group Index that may be explicitly provided inthe command. For example, the two spare bits of the existing “TimingAdvance Command MAC Control Element” may be used, or a new type of MACcontrol element including the group index may be defined. When a TimingAdvance Command MAC CE is received, the WTRU may identify the UL CC setusing the Group Index and may start/restart the TAT for thecorresponding UL CC set.

Alternatively, the network may use any other form of dedicated signalingto provide the WTRU with the TA value. The network may embed the CC“group index” in this message to indicate which UL CC set may beassociated with this TA value.

Again alternatively, for applying the TA value to a specific UL CC setupon expiration of an UL CC set's TAT, the WTRU may follow the sameprocedure as initial TA establishment as described previously tore-establish UL timing alignment. Re-acquiring the TA may be done if andwhen necessary. Alternatively, the WTRU may determine based on the groupindex provided in dedicated signaling which RACH resources to use tore-establish the corresponding UL CC set's TA. The WTRU may then repeatthe Random Access procedure as described above.

In another alternative, the network may use the existing Timing AdvanceCommand MAC CE, or any other form of dedicated signaling, to provide theTA value previously used for the corresponding UL CC set. The networkmay use this mechanism within a reasonable amount of time (a new timercan be defined for this) after the expiration of the TAT. The WTRU maythen use this TA value to start/restart the corresponding TAT withoutperforming an RA procedure for this UL CC set.

Upon expiration of the TAT for a specific UL CC set (or for allconfigured UL CC's in case where there is a single TAT), the WTRU mayflush all HARQ buffers corresponding to the UL-SCH of an UL carrier partof the UL CC set.

Corresponding local NACKs may also be indicated to the RLC sub-layer.Any Physical Uplink Control Channels (PUCCH) or SRS configuration of aUL carrier which is part of the UL CC set may be released uponexpiration of the TAT. For any DL carrier for which feedback istransmitted over such PUCCH, the WTRU may perform at least one of thefollowing, except for a specific DL carrier, such as the PCell DL. TheWTRU may: stop PDSCH processing (e.g., buffering/decoding) for this DLcarrier, de-activate the DL carrier, release the PDSCH configuration forthis DL carrier, release the PDCCH configuration for this DL carrier,release the PRACH configuration applicable to this DL carrier, and/orrelease any part of the configuration pertaining to the DL carrier.

Any uplink grant applicable to an UL carrier part of the UL CC set maybe cleared upon expiration. In addition, any downlink assignment forwhich feedback may be provided on resources corresponding to an ULcarrier which may be part of the UL CC set may be cleared.

The PUSCH configuration on a UL carrier which is part of the UL CC setmay be released. This, however, may not apply to certain UL carrier(s),such as the PCell UL.

The PUSCH on a UL carrier which is part of the UL CC set may bedeactivated. This however, may not apply to certain UL carrier(s), suchas the PCell UL. The PUSCH on these carriers could be reactivated uponsubsequent reception of a timing advance command applicable to the UL CCset.

A PUCCH configuration that may be received using dedicated signaling,for example, an R10 configuration for an explicit resource allocationfor HARQ and/or for CQI/PMI/RI for control information corresponding tomultiple DL CCs, of an UL CC (e.g. a PCell UL) of a WTRU's configurationwhich is part of the UL CC set may be invalidated. For example, the WTRUmay maintain (at least part of) the dedicated PUCCH configuration butmay not transmit on a resource corresponding to the configuration,possibly until the WTRU has a valid timing advance for the UL CC. Thismay be because of TAT expiry for PCell UL, and the WTRU mayinvalidate/remove PUCCH A/N on PCell UL and revert to R8/9 A/N behavior.The WTRU may revert to dynamic selection of A/N resource for HARQfeedback transmitted in the UL CC (e.g, the PCC); and/or the WTRU maystop transmission of CQI/PMI/RI on the PUCCH resources for CQI/PMI/RI.

A PUCCH configuration that may be received using dedicated signaling mayalso be released, e.g., the WTRU may completely remove, or remove atleast a part of, the dedicated PUCCH configuration. For example, an R10configuration for an explicit resource allocation for HARQ A/N and/orfor CQI/PMI/RI for control information corresponding to multiple DL CCs,of an UL CC (e.g. a PCell UL) of a WTRU's configuration which is part ofthe UL CC set may be released. The WTRU may revert to dynamic selectionof A/N resource for HARQ feedback transmitted in the UL CC (e.g., thePCC); and/or the WTRU may stop transmission of QI/PMI/RI on the PUCCHresources for CQI/PMI/RI.

As an example, upon TAT expiry of the PCell UL, the WTRU may invalidatethe R10 explicit PUCCH A/N resource allocation and/or release the R10PUCCH configuration for CQI/PMI/RI of the PCell UL.

Because of TAT expiry for a SCell UL with a PUCCH configuration (perhapsassuming PUCCH and PCC are decoupled and PCell UL may be defined basedon PCell DL), the WTRU may switch to a PUCCH configuration of the PCellUL. A dedicated PUCCH configuration (R10 configuration for HARQ A/Nand/or for CQI/PMI/RI for control information corresponding to multipleDL CCs) of a UL CC (e.g., a PCell UL) of the WTRUs configuration, whichUL CC is still considered time aligned (e.g., the UL CC is not part ofthe UL CC set for which TA is no longer valid), may be reconfigured. Forexample, the WTRU may select a different resource from its PUCCH A/Nconfiguration such that a WTRU transmits uplink control information onthe reconfigured resource on the UL CC which still may have valid TA(e.g., a PCell UL). Also by way of example, this may be consideredequivalent to switching between a configured resource (e.g., for A/N) ona first UL CC to a configured resource on a second UL CC (e.g., a PCellUL) upon loss of TA for the first UL CC, or using a different dedicatedresource (e.g., for CQI/PMI/RI) on e.g., a PCC upon expiration of TA(and possibly implicit deactivation) for one or more SCells.

Because of TAT expiry, the WTRU may only be allowed to perform RACH forPCell DL. Embodiments contemplate that the WTRU may invalidate and/orremove the RACH resources from its configuration, which resourcescorrespond to an SCell UL which is part of the UL CC set for which TAmay no longer be valid. In other words, in some embodiments, the WTRUmay only initiate random access (RACH) on a UL/DL CC pair (e.g., thePCell) using single carrier operation according, to R8/9 selection andtransmission principles.

Also because of TAT expiry, the WTRU may later regain a valid TA, it mayrevert to R8/9 of all UL/DL CC pairs of its configuration. The WTRU mayrevert to a R8/9 behavior for A/N transmissions on PUCCH when itsubsequently recovers a valid TA for the UL CC, transmitting on a PUCCHresource of the UL CC which resource is determined based on at least oneof: the UL/DL linking of the DL CC in which it successfully decodes aPDCCH for a DL assignment; or using a resource in the PUCCH regioneither broadcasted in, the SI of the corresponding DL CC (e.g., for aPCC) or received in a dedicated manner (e.g., for a SCC).

As an example, upon TAT expiry a WTRU may keep its multicarrierconfiguration including resources for performing random access in aSCell of its configuration; in this case, for each CC pair (e.g. eithera PCell or a SCell pair of the WTRU's configuration) the WTRU may applyRel-8/9 behavior for A/N transmission on PUCCH once it recovers a validTA, e.g., when receiving a TA Command during the random accessprocedure.

Embodiments contemplate that a WTRU may revert to a single carrier(e.g., R8/9) operation: where the serving cell may correspond to thedownlink primary carrier (e.g., PCell) prior to the timer expiry; or ifthe WTRU has no valid time alignment for any UL CC set (e.g., no timingadvance timer is running).

All of the methods as described above may be applicable to TAT expiry,and also may be equally applicable for implicit SCell deactivation (A/Nand CQI). The above methods may also be applicable upon deactivation ofan SCell (either explicit, or implicit, e.g., using a timer differentthan the TAT but with similar properties in that it forbids a WTRU touse uplink resources corresponding to the deactivated SCell) or explicitreconfiguration which removes a UL CC (e.g. a SCell UL) of the WTRUsconfiguration.

In addition, for methods above where the WTRU may revert to R8/9behavior for transmission of A/N on PUCCH (e.g., dynamic selection ofPUCCH resource). For example, a TAT may expire and the WTRU may have aconfiguration including at least one SCell DL, it may not be possiblefor the WTRU to transmit HARQ A/N feedback and/or CQI/PMI/RI for morethan one DL CC (e.g., a WTRU may have multiple DL CCs and end up in asituation where it may only use a single R8/9 PUCCH resource for A/Nduring a RACH procedure) until it first recovers the means to transmituplink control information for more than one carrier in a subframe,e.g., until it is reconfigured. In particular if a WTRU may onlytransmit A/N feedback in a single UL CC (e.g., the PCell UL) during therandom access procedure. For random access, reconfiguration may happenno earlier than upon reception of RA “msg4” for contention-based RA, orno earlier than the first PDSCH assignment following reception of RA“msg2” in case of contention-free RA.

Embodiments contemplate that, where a WTRU receives more than one DLassignment in a given subframe (the WTRU may successfully decodemultiple PDCCH in a given subframe), the WTRU, which may consider thePDSCH of the PCell DL, may generate A/N feedback according to the DLtransmission received on the PCell DL only.

In case where a WTRU receives more than one DL assignment in a givensubframe (the WTRU may successfully decode multiple PDCCH in a givensubframe), the WTRU, which may consider the PDSCH of the DL CC used forthe ongoing RACH procedure, may generate A/N feedback for the DLtransmission received on the DL CC associated/linked to the UL CC usedfor transmission of RA msg1 (e.g., a RACH preamble) and/or fortransmission of RA msg3 (e.g., a transmission using the resourcesgranted in a RA Response previously received).

For any of the embodiments described previously, the WTRU may (for A/Nfeedback) either transmit on a PUCCH resource on a PCell UL according toR8/9 selection and transmission or the WTRU may transmit R8/9 A/N onPCell UL. The WTRU may also transmit on a PUCCH resource on the UL CCassociated/linked to the DL CC for which the A/N feedback was generated,according to R8/9 selection and transmission; or transmit R8/9 A/N onthe linked SCell UL; or the WTRU may refrain from transmission, e.g.,the WTRU may not transmit any feedback, and possibly may ignore thereceived DL assignment or may consider this as an error situation.

Methods are disclosed for maintaining time alignment with multipleuplink carriers that include determining that all UL carriers part ofthe same frequency band are part of the same UL CC set. The WTRU signalscapability of using multiple TAs by defining a group index of a few bitsfor each UL CC set. The Timing Advance Command received in the RandomAccess Response message is used to apply the TA value to each UL carrierof the UL CC set. The WTRU may determine which UL CC set the TA valueapplies to based on which DL carrier the command was transmitted from,for example by way of a Timing advance command MAC control element. TheWTRU may determine which UL CC set the TA value applies to based on theGroup Index being explicitly provided in the command. The WTRU releasesat least a part of a multicarrier configuration (e.g., the configurationof one or more SCells) upon TAT expiry. For example, the WTRU mayrelease the configuration for all SCells for which the respective SCellUL is part of the UL CC set for which the timing alignment is no longervalid. Alternatively, for example, the WTRU may release theconfiguration for all SCells when the timing alignment of the PCell isno longer valid.

It should be understood that any of the embodiments described hereindirected to the function or capability of the WTRU and/or a base node(or base station or eNodeB) may be implemented by one or more processorsconfigured to perform the disclosed function or capability. For example,the processor 118 described with regard to FIG. 1B may be configured toperform some or all of the various WTRU functions and capabilitiesdisclosed herein, in whole or in part. Also by way of example, aprocessor included in an base station (base node) or eNodeB describedwith regard to FIG. 1C may be configured to perform some or all of thevarious base node or eNodeB functions and capabilities disclosed herein,in whole or in, part.

In FIG. 2, exemplary embodiments contemplate a wireless transmit/receiveunit (WTRU) that may be configured, at least in part, to, at 202,identify one or more uplink carriers with which the WTRU may be capableof operating, or one or more uplink carriers that may be operating on awireless communication network. At 204, the WTRU may also be configuredto determine one or more uplink component carrier sets (UL CC sets).Each of the UL CC sets may comprise one or more of the uplink carriersand each of the one or more uplink carriers that may comprise arespective UL CC set may be capable of operating with the same TimingAdvance (TA). The WTRU may be configured to determine the one or moregroups of UL CC sets based on a predetermined identification of which ofthe one or more uplink carriers may correspond to the one or more UL CCsets. At 206, the WTRU may also be configured to select at least one ULCC set and, at 208, identify at least one of the one or more uplinkcarriers that may be capable of random access channel (RACH)communication for the selected at least one UL CC set. At 210, the WTRUmay be configured to initiate a RACH communication on at least one ofthe identified one or more uplink carriers for the selected at least oneUL CC set and, at 212, to receive a TA value in response to the RACHcommunication. The WTRU may be further configured, at 214, to apply theTA value to each of the one or more uplink carriers that comprise theselected at least one UL CC set.

Embodiments contemplate that the selected at least one UL CC set mayhave an associated Time Alignment Timer (TAT) and, at 216, the WTRU maybe further configured to either start the TAT or restart the TAT.Referring to FIG. 3, the WTRU may also be configured, at 302, to receivea signal via a downlink carrier where the signal may include a TA value.The WTRU may, at 304, identify at least one of the one or more uplinkcarriers that may be paired with the downlink carrier and, at 306,identify at least one of the one or more UL CC sets that may correspondto the at least one of the one or more uplink carriers that may bepaired with the downlink carrier. The WTRU may, at 308, apply the TAvalue to each of the one or more uplink carriers that comprise theidentified at least one of the one or more UL CC sets.

Referring to FIG. 4, embodiments contemplate that one or more UL CC setsmay correspond to respective frequency bands and the WTRU may beconfigured, at 402, to receive a signal via a downlink carrier, wherethe signal may include a TA value. The WTRU may be configured, at 404,to identify a frequency band corresponding to the downlink carrier andidentify at least one of the one or more UL CC sets whose respectivefrequency band may correspond to the frequency band of the downlinkcarrier. The WTRU may, at 406, apply the TA value to each of the one ormore uplink carriers that may comprise the identified at least one ofthe one or more UL CC sets.

Referring to FIG. 5, embodiments contemplate that the a selected atleast one UL CC set may includes at least one uplink carrier with adedicated physical uplink control channel (PUCCH) configuration. A WTRUmay be, at 502, configured to cease transmitting on a resourcecorresponding to the PUCCH upon an expiration of the TAT. Alternativelyor additionally, the WTRU may be, at 504, configured to remove at leasta part of the PUCHH configuration upon an expiration of the TAT. Alsoalternatively or additionally, the WTRU may be, at 506, configured toremove one or more RACH resources from the configuration of the selectedat least one UL CC set upon an expiration of the TAT.

Referring to FIG. 6, embodiments contemplate a wireless networkresource, such as an evolved Node B (eNodeB), may be configured, atleast in part, at 602, to identify one or more uplink carriers withwhich the eNodeB (or the wireless network) may be capable of operating.The eNodeB may be configured, at 604, determine one or more indices.Each of the one or more indices may correspond respectively to one ormore uplink component carrier sets (UL CC sets), Also, each of the UL CCsets may comprise one or more of the uplink carriers, and each of theone or more uplink carriers that comprise a respective UL CC set may becapable of operating with the same Timing Advance (TA). The eNodeB may,at 606, be configured to transmit the one or more indices.

Embodiments contemplate that the eNodeB may be configured to, at 608,receive a RACH communication on at least one of the one or more uplinkcarriers that comprise at least one of the one or more UL CC sets andmay, at 610, transmit a TA value in response to the RACH communication.The TA value may be applicable to each of the one or more uplinkcarriers that comprise the at least one of the one or more UL CC sets.Alternatively or additionally, the eNode B may be, at 612, configured totransmit a signal, where the signal may include a TA value and anindicator. The indicator may be a Group Index, for example. Theindicator may indicate at least one of the one or more UL CC sets towhich the TA value may be applicable.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art will appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer readable medium for execution by a computeror processor. Examples of computer-readable media include electronicsignals (transmitted over wired or wireless connections) andcomputer-readable storage media. Examples of computer-readable storagemedia include, but are not limited to, a read only memory (ROM), arandom access memory (RAM), a register, cache memory, semiconductormemory devices, magnetic media such as internal hard disks and removabledisks, magneto-optical media, and optical media such as CD-ROM disks,and digital versatile disks (DVDs). A processor in association withsoftware may be used to implement a radio frequency transceiver for usein a WTRU, UE, terminal, base station, RNC, or any host computer.

What is claimed is:
 1. A wireless transmit/receive unit (WTRU),comprising: a processor, the processor configured, at least to:determine one or more sets of serving cells, each of the one or moresets of serving cells including at least one serving cell with aconfigured uplink component carrier (UL CC sets), each of the UL CC setsrespectively associated with a group index of one or more group indices,each UL CC set of the one or more UL CC sets respectively including oneor more uplink carriers that are associated with a same group index withwhich the UL CC set is associated, each of the one or more uplinkcarriers that are included in a respective UL CC set being configured tooperate with a same Timing Advance (TA) of one or more Timing Advances(TAs), each of the UL CC sets having a respectively associated referencecarrier providing a TA of the one or more TAs; receive a first TA valuevia a first reference carrier, the first reference carrier associatedwith a first UL CC set; and apply the first TA value to the one or moreuplink carriers that are included in the first UL CC set.
 2. The WTRU ofclaim 1, wherein the processor is further configured to: selecting thefirst UL CC set; identifying at least one of the one or more uplinkcarriers of the first UL CC set that are capable of random accesschannel (RACH) communication; initiating a RACH communication on atleast one of the identified one or more uplink carriers of the first ULCC set; and receiving the first TA value in response to the RACHcommunication.
 3. The WTRU of claim 2, wherein the first TA value isapplied using a Timing Advance Command received in a Random AccessResponse message received in response to the RACH communication.
 4. TheWTRU of claim 2, wherein the first UL CC set has an associated TimeAlignment Timer (TAT) and the processor is further configured to eitherstart the TAT or restart the TAT.
 5. The WTRU of claim 3, wherein theTiming Advance Command further includes a Timing Advance Command MediumAccess Control (MAC) control element.
 6. The WTRU of claim 4, whereinthe first UL CC set includes at least one uplink carrier with adedicated physical uplink control channel (PUCCH) configuration, and theprocessor is further configured to cease transmitting on a resourcecorresponding to the PUCCH upon an expiration of the TAT.
 7. The WTRU ofclaim 4, wherein the first UL CC set includes at least one uplinkcarrier with at least one of a dedicated physical uplink control channel(PUCCH) configuration or a sounding and reference signal (SRS)configuration, and the processor is further configured to remove atleast a part of either the PUCCH configuration or the SRS configurationupon an expiration of the TAT.
 8. The WTRU of claim 4, wherein theprocessor is further configured to remove one or more Hybrid AutomaticRepeat Request (HARQ) buffers corresponding to the first UL CC set uponan expiration of the TAT.
 9. The WTRU of claim 1, wherein the firstreference carrier is a first downlink (DL) carrier, the first DL carrierbeing associated with the first UL CC set.
 10. The WTRU of claim 2,wherein the initiating the RACH communication on the at least one of theidentified one or more uplink carriers of the first UL CC set includesinitiating a contention free based RACH procedure.
 11. A method forestablishing timing advance, comprising: determining one or more sets ofserving cells, each of the one or more sets of serving cells includingat least one serving cell with a configured uplink component carrier (ULCC sets), each of the UL CC sets respectively associated with a groupindex of one or more group indices, each UL CC set of the one or more ULCC sets respectively including one or more uplink carriers that areassociated with a same group index with which the UL CC set isassociated, each of the one or more uplink carriers that are included ina respective UL CC set being configured to operate with a same TimingAdvance (TA) of one or more Timing Advances (TAs), each of the UL CCsets having a respectively associated reference carrier providing a TAof the one or more TAs; receiving a first TA value via a first referencecarrier, the first reference carrier associated with a first UL CC set;and applying the first TA value to the one or more uplink carriers thatare included in the first UL CC set.
 12. The method of claim 11, furthercomprising: selecting the first UL CC set; identifying at least one ofthe one or more uplink carriers of the first UL CC set that are capableof random access channel (RACH) communication; initiating a RACHcommunication on at least one of the identified one or more uplinkcarriers of the first UL CC set; and receiving the first TA value inresponse to the RACH communication.
 13. The method of claim 11, furthercomprising: executing at least one of a start or a restart of a TimeAlignment Timer (TAT), the TAT being associated with the first UL CCset.
 14. The method of claim 12, further comprising receiving a TimingAdvance Command in a Random Access Response message received in responseto the RACH communication, wherein the first TA value is applied usingthe Timing Advance Command.
 15. The method of claim 12, wherein theTiming Advance Command further includes a Timing Advance Command MediumAccess Control (MAC) control element.
 16. The method of claim 13,wherein the first UL CC set includes at least one uplink carrier with adedicated physical uplink control channel (PUCCH) configuration, and themethod further comprises ceasing transmitting on a resourcecorresponding to the PUCCH upon an expiration of the TAT.
 17. The methodof claim 13, wherein the first UL CC set includes at least one uplinkcarrier with at least one of a dedicated physical uplink control channel(PUCCH) configuration or a sounding and reference signal (SRS)configuration, and the method further comprises removing at least a partof either the PUCCH configuration or the SRS configuration upon anexpiration of the TAT.
 18. The method of claim 13, wherein the methodfurther comprises removing one or more Hybrid Automatic Repeat Request(HARQ) buffers corresponding to the first UL CC set upon an expirationof the TAT.
 19. The method of claim 11, wherein the first referencecarrier is a first downlink (DL) carrier, the first DL carrier beingassociated with the first UL CC set.
 20. The method of claim 12, whereinthe initiating the RACH communication on the at least one of theidentified one or more uplink carriers of the first UL CC set includesinitiating a contention free based RACH procedure.